Abstract:

We propose a bio-inspired control mechanism for dynamically
programmable analogue devices. Our control mechanism is evolved using
conventional genetic algorithms; its uniqueness lies in a feedback loop
that allows the devices to change their configuration by interacting
with the evolved genome as internal or external conditions alter. In our
proposed mechanism, a digital genome encodes for the components and
configuration of (potentially many) analogue circuits. Most solutions in
evolutionary computation contain the complete realisations of the
genotype and there is no interaction with the genome once the solution
has been achieved. Our system uses circuit outputs that feedback into
the digital genome, triggering a regulatory control mechanism. As the
circuits inputs change, outputs are able to match binding sites on
the genome, allowing the expression of new circuits. The
binding signature sequences are evolved with the genome, and can be
specific or contain wildcard positions, making the matching
process flexible. The genome is represented in a form suitable for
Cartesian Genetic Programming. It encodes an analogue circuit as a
feed-forward directed graph, with each node in the graph specifying the
configuration of an analogue component. As the circuit responds to its
inputs, the outputs are Fourier transformed and digitised, to give a
series of bin values. These output values are matched against binding
signatures on the genome. If a match is found, the circuit
reconfiguration specified by that binding site takes place. Our
experiment uses dynamically programmable Analogue Signal Processors
(dpASPs) from Anadigm to achieve rapid re-configuration. These
chips are destined to replace many ASICs and offer potentially
disruptive technology wherever digital logic has to interface with the
real world. The technology permits us to investigate the complex world
of analogue signal processing with evolutionary search algorithms that
can be tested
in silico
rather than in simulation. The ability
to reconfigure analogue circuits within a
single clock cycle
means that a new breed of analogue control systems can be created. Our
next steps are to evolve genomes that encode a set of reconfigurable
circuits capable of performing a variety of tasks in changing
environments. For example, a filter might reconfigure as input signal
characteristics change; a robot controller might reconfigure from vision
to ultrasound as light levels change, or from exploitation to
exploration behaviour when inputs indicate that a resource is being
exhausted.